Bushing type electric circuit breaker



Feb. 19, 1952 o. TANGE ETAL BusHINC TYPE ELECTRIC CIRCUIT BREAKER FiledMay 25, 1949 I f Am Patented Feb. 19, 1952 BUSHING TYPE ELECTRIC CIRCUITBREAKER toyuki Tange and Seiiti Morita, Taga-Mat, Tag'a-Gun, Japan,assignors to Hitachi Limited, Tokyo, Japan, a corporation of JapanApplication May 25, 1949, Serial No. 95,294

3 Claims. (Cl. Z110- 150) rlhis invention relates to electric circuitbreakers, and more particularly to an electric circuit breaker immersedin an oil filled bushing, and has for its object to provide an electriccircuit breaker having higher insulating strength between two electrodesin case of opening circuit.

A further object is to stabilize the circuit interrupting effect afterthe electric arc had been extinguished.

Another object of the invention is to pre- 'vent the creeping dischargeor flash over bethe contact.

With the above objects in view the invention consists of novel detailsof construction and combination of parts hereinafter fully described andclaimed.

Referring now to the drawing;

A single gure is a sectional elevation of a bushing type oil circuitbreaker embodying this invention.

Referring now to the drawing, I designates an insulator cylinder, suchas a porcelain bushing, which is oil-tightlyv sealed at its bottom by ametal cover II and secured to a metal cap I2 put on supporting insulatorI3. III designates an upper metal casing which is secured tightly to thetop of the bushing I0 and encloses therein a suitable switch operatingmechanism I5. I6 designates an operating insulator for the mechanism I`According to the present invention, a rprotective insulator cylinder I'Iis suspended from the upper casing I4 by means of metal pieces I8 and acylinder I9 of insulating material such as Bakelite cylinder is put inthe cylinder II and secured to its bottom 2D. A number of arcsuppressing chambers 2I are formed in the cylinder I9 and a lowerstationary electrode 22 is xed in the cylinder I9. 23 is a conductor rodtting into the lower contact piece 2.4 fixed to the bottom plate II andengaging in a hole 25. 26 is a terminal lead, 21 an upper stationaryelectrode fixed to the pillar 28. 29 designates a moving electrodepassing through the' member 2'I and guided thereby, 30 is an upperterminallead. It is an essential feature of the invention that theinsulating oil gap G is provided between the top of the arcsuppressingcylinder I9 and the lower end of the cylinder 3| enclosing the upperfixed electrode 21 and forming the circuit interrupting chamber 32therein. 33 represents insulating oil. v

The above construction is most effective in positively 'increasing theinsulating strength beteen the fixed electrode 22 and the lower end ofthe moving electrode 29 in its circuit open pcsition and in absolutelypreventing the rearcing phenomena since gases generated and followingthe moving electrode 29 when the electrode is moved upwards apartingfrom the lower electrode 22 can freely expand and iind the way throughthe oil gap G into the annular oil space between the cylinders I'I andI9, and finally the lower end of the electrode 29 passes through the oilgap G and retires into the chamber 32 so that the electrode 29 caneasily get rid of gaseous zone. Moreover according to the presentinvention, the arrangement of the circuit breaker allows no possibilityof moistures entering into the protective cylinder I'I through thebottom plate 20 and of depositing carbo- `naceous substances on theinner surfaces of arc suppressing cylinder so that the danger of causingcreeping discharge along the inner surface of the insulating cylinder.Thus the present invention is effective in promoting circuitinterrupting ability of such circuit breakers and maintaining higherdielectric strength of insulating Aa fixed contact adjacent the bottomof said protective insulator cylinder, a movable contact reciprocablymounted adjacent the top of said protective insulator cylinder, meansfor reciprocating the movable contact into and out of engagement withthe fixed contact, an arc suppressing cylinder of lesser diameter thanthe protective insulator cylinder mounted within the latter, formingwith same part of an oil chamber and enclosing the fixed contact, aplurality of partitions having aligned apertures therein of slightlygreater diameter than the movable contact through which the movablecontact is adapted to pass with close clearance, and forming a series ofoil filled arc suppressing chambers,

' an insulator cylinder of lesser diameter than the protective insulatorcylinder positioned within the latter in alignment with the arcsuppressing cylinder forming with the protective insulator cylinder partof the oil chamber and having a bottom with an aperture therein and saidbottom being spaced from the top of the arc suppressing cylinder to forman oil filled gap as part of the oil chamber, and means forreciprocating said movable contact through the aperture in the bottom ofthe insulator cylinder and the apertures in the partitions in theV arcsuppressing cylinder to and from engagement with the fixed contact.

'2. An electric circuit breaker comprising an insulator bushing having aclosed bottom forming an oil tank, an insulated support for theinsulator bushing, a casing secured in the top of the insulator bushing,a protective insulator cylinder suspended from the casing and positionedwithin the insulator bushing and extending downwardly from the top ofthe latter into the oil tank, an arc suppressingcylinder of lesserdiameter than the protective insulator cylinder positioned Within theprotective insulator cylinder and secured to the bottom of the latterand forming with same part of a main oil chamber, a fixed contact withinthe arc suppressing cylinder, means within the arc suppressing cylinderforming a series of separate oil lled arc suppressing chambers, aninsulator cylinder of lesser diameter than the protective insulatorcylinder suspended from said casing and positioned within the protectiveinsulator cylinder in alignment with the arc suppressing cylinderforming with the protective insulator cylinder part of the main oilchamber I having a bottom with an aperture therein and with said bottomforming with the arc suppressing cylinder an oil gap as part of the mainoil chamber, a movable contact reciprocably mounted adjacent the top ofsaid insulator cylinder, guide means at the top of the insulatorcylinder for said movable contact and forming with the bottom of theinsulator cylinder an arc extinguishing chamber, and means within saidcasing for reciprocating said movable contact through the arcsuppressing chamber, the gap between the insulator cylinder and the arcsuppressing cylinder, and the oil lled arc suppressing chambers withinthe arc suppressing cylinder into and out of engagement with the xedcontact whereby the insulating strength between the movable and fixedcontacts is quickly restored upon the return stroke of the former by thearc being extinguished in the oil lled arc suppressing chambers withinthe arc suppressing cylinder, the gases emitted from the top of the arcsuppressing cylinder being prevented from entering the arc suppressingchamber in the insulator cylinder as the movable contact is withdrawnthrough the aperture in the bottom of the latter by being dispersed inthe oil gap between the insulator cylinder and the arc suppressingcylinder.

protective insulator cylinder positioned within4 the latter and securedto the bottom of the latter and forming with same part of a main oilchamber, means within the arc suppressing cylinder forming a series ofseparate oil nlled arc suppressing chambers, an insulator cylinder oflesser diameter than the protective insulator cylinder suspended fromsaid casing and positioned Within the protective insulator cylinder inalignment with the arc suppressing cylinder forming with the protectiveinsulator cylinder part of the main oil chamber and having a bottom withan aperture therein and with said bottom forming with the arcsuppressing cylinder an oil gap as part of the main oil chamber, amovable contact reciprocably mounted adjacent the top of said insulatorcylinder, guide means at the top of the insulator cylinder for saidmovable contact and forming with the bottom of the insulator cylinder anarc extinguishing chamber, and means within said casing forreciprocating said movable contact through the arc suppressing chamber,the

aperture in the bottom of the insulator cylinder,

the gap between the insulator cylinder and the arc suppressing cylinder,and the oil filled arc suppressing chamber within the arc suppressingcylinder into and out of engagement with the iixed contact whereby theinsulating strength between the movable and fixed contacts is quicklyrestored upon the return stroke of the former by the arc beingextinguished in the oil lled arc suppressing chambers within the arcsuppressing cylinder, the gases emitted from the top of the arcsuppressing cylinder being prevented from entering the arc suppressingchamber in the insulator cylinder as the movable contact is withdrawnthrough the aperture in the bottom of the latter by being dispersed inthe oil gap between the insulator cylinder and the arc suppressingcylinder.

OTOYUKI TANGE.

SEIITI MORITA.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,155,814 Hewlett Oct. 5, 19152,227,134 Hara Dec. 31, 1940 2,475,765 Wallace et al. July 12, 1949`

